tbuckley/cabot-search huggingface dataset:
Abstract PR011: The glutathione S-transferase, Gstt1 is a robust driver of survival and dissemination in metastases
Authors: Christina M. Ferrer
Journal: Cancer Research (2023)

Abstract Identifying adaptive mechanisms of metastatic cancer cells remains an elusive question in the treatment of metastatic disease, particularly in pancreatic cancer (PDA), where the majority of patients present with metastatic lesions at the time of diagnosis. A loss-of-function shRNA targeted screen in metastatic-derived cells identified Gstt1, a member of the glutathione S-transferase superfamily, as uniquely required for metastasis and dissemination however dispensable for primary tumor growth. Gstt1 is expressed in early disseminated tumor cells (DTCs), is retained within a subpopulation of slow-cycling cells within established metastases and its inhibition completely abolished macrometastatic lesions. This distinct Gstt1high population is highly metastatic and retains slow-cycling phenotypes, EMT features, and DTC characteristics compared to the Gstt1low population. Mechanistic studies indicate that in this subset of cells, Gstt1 maintains metastases by binding to and modifying intracellular fibronectin, regulating fibronectin secretion from cancer cells and deposition into the metastatic microenvironment. We identified Gstt1 as a novel mediator of metastasis, highlighting the importance of metastatic heterogeneity and its influence on the metastatic tumor microenvironment. Citation Format: Christina M. Ferrer. The glutathione S-transferase, Gstt1 is a robust driver of survival and dissemination in metastases [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr PR011.
Abstract IA014: Effects of fluid shear stress on circulating tumor cells
Authors: Michael Henry
Journal: Cancer Research (2023)

Abstract To colonize distant organ sites, cancer cells originating in solid tissues must traverse the circulatory system. How circulating tumor cells (CTCs) survive various biological and mechanical insults during this journey remains unclear. Mechanical challenges to CTCs include exposure to fluid shear stress (FSS) which ranges over several orders of magnitude throughout the circulatory system. To assess the effects of FSS on cancer cells, we developed a simple model to apply brief pulses of fluid shear stress to cancer cells in suspension. Surprisingly, we found that cancer cell lines, originating from many different tissues are more resistant to destruction by FSS than normal epithelial counterparts. FSS resistance is conferred on normal epithelial cells by transforming oncogenes and is evident in cancer cells acutely isolated from primary tumor tissues from mice and humans. Thus, FSS resistance is a conserved phenotype of viable transformed cells. FSS resistance is an active biological mechanism in viable cancer cells, dead and dying cancer cells are readily destroyed by FSS. In cancer cells, initial exposure to FSS results in rapid cell stiffening unlike non-transformed cells. This change in contractility of cancer cells exposed to FSS is associated with activation of RhoA/C GTPases. Correspondingly, in cancer cells exposed to FSS, there is a rapid increase in cortical F-actin that depends on formin activity, and myosin II activity is elevated. Both F-actin remodeling and myosin II activity are required for FSS resistance in vitro. Myosin II activity is also required for required for FSS resistance of experimental CTCs in vivo. Treatment of PC-3 cells with blebbistatin, a myosin II inhibitor, reduced the number of intact CTCs lodged in the lung and increased the number of CTCs destroyed immediately following tail vein injection. Moreover, treatment of mice bearing orthotopic prostate tumors with a non-toxic dose of blebbistatin reduced the levels of CTCs over 20-fold within 3h of treatment. As FSS exposure activates Rho GTPases, which are known to influence invasive and proliferative capacity of metastatic cells, more recently we have been investigating how FSS exposure may prime CTCs for metastasis. Exposure of both PC-3 and MDA-MB-231 cancer cell lines to FSS enhances metastatic colonization, invasive behavior in vitro and anchorage-independent proliferation. Ongoing efforts are to define the mechanisms that underly these emergent behaviors in response to FSS. In summary, we have found that viable CTCs actively resist destruction by FSS via a RhoA-dependent mechano-adaptive mechanism and that surviving cancer cells exposed to FSS exhibit enhanced metastatic potential. Citation Format: Michael Henry. Effects of fluid shear stress on circulating tumor cells [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr IA014.
Abstract A012: NAT10 promotes metastasis through enhancer remodeling of cancer cells
Authors: Ruhul Amin, Ngoc-Han Ha, Jordan L. Meier, Kent W. Hunter
Journal: Cancer Research (2023)

Abstract Distant organ metastases account for the majority of the cancer-related death. However, the detailed mechanism underlying the metastatic potential of cancer cells is poorly understood. We have previously shown than NUP210-dependent nuclear pore-associated chromatin-bound protein complex is involved in cellular mechanotransduction and metastasis in breast cancer. Although NAT10, an RNA cytidine acetyl transferase has been shown to interact with this protein complex, specific function of NAT10 in metastasis is not well understood. Using allograft and genetically engineered highly metastatic PyMT mouse model, we found that the loss of NAT10 significantly decreases lung metastasis in mice. NAT10 is mainly localized to the nucleolus and nucleoplasmic compartment of the cancer cells. Current understanding suggests a role of NAT10 in acetylation of mRNAs and ribosomal RNAs. In contrast to its role as an RNA acetylase, we uncovered a new mechanism of NAT10 in cancer cells. Using co-immunoprecipitation followed by mass spectrometry and chromatin immunoprecipitation followed by high throughput sequencing (ChIP-seq), we found that NAT10 is interacting with super-enhancer associated protein complex. RNA-seq analysis revealed that the loss of NAT10 leads to dramatic transcriptional suppression of super-enhancer driven genes including MYC. Mechanistically, using mass spectrometry-based quantification of protein acetylation, we showed that the loss of NAT10 leads to decreased acetylation of enhancer-associated Histone H4 and H3 modification. NAT10 loss also leads to increased heterochromatin-forming histone methylation within the cell nuclei. Our study revealed a distinct role of NAT10 as an enhancer remodeler in metastatic cancer cells. Therefore, NAT10 could be a potential therapeutic target in preventing metastatic disease. Citation Format: Ruhul Amin, Ngoc-Han Ha, Jordan L. Meier, Kent W. Hunter. NAT10 promotes metastasis through enhancer remodeling of cancer cells [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr A012.
Abstract IA010: Hypomethylation of immune-related loci contribute to prostate tumorigenesis
Authors: Daniel A. Haber, Hongshan Guo, Ben S. Wittner, Joanna A Vuille, Michael S. Lawrence, Chin-Lee Wu, Mehmet Toner, David T. Miyamoto, Shyamala Maheswaran
Journal: Cancer Research (2023)

Abstract Cancer-associated alterations in DNA methylation include hypermethylation of focal CpG islands within promoters, as well as hypomethylation of large stretches of gene-poor chromosomal domains, so called Partially Methylated Domains (PMDs). While CpG island hypermethylation is associated with silencing of tumor suppressor genes, the functional consequences of hypomethylation are uncertain. PMDs may be cause or consequence of cancer cell proliferation, and they have been associated with transcriptional de-repression of repetitive sequences, as well as histone modification-triggered silencing of rare protein encoding genes within these domains. In studying Circulating Tumor Cells (CTCs) isolated from blood specimens of patients with prostate cancer, we mapped PMDs at the single cell level, identifying a set of 40 “core PMDs” that are shared across cancer cells, within and across different individuals, as well as in prostate cancer cell lines. By analyzing single nuclei from micro-dissected early-stage prostate tumors, we find that hypomethylation of these core PMDs occurs early during prostate tumorigenesis. Core PMDs are highly enriched for immune-related genes, many of which are co-located within a single chromosomal locus targeted for hypomethylation-associated silencing. Nested between adjacent PMDs, we also identify domains that have retained DNA methylation (Preserved Methylation Islands; PMIs), which have sharply demarcated borders, spanning one or a small number of genes. In contrast to PMDs, PMIs are enriched for cell proliferation-associated genes. Together, these observations suggest that hypomethylation-associated silencing of immune-related genes, with sparing of adjacent proliferation-associated genes, is an early event in prostate cancer development. These large-scale chromosomal modifications are detectable within CTCs and may present diagnostic opportunities. Citation Format: Daniel A. Haber, Hongshan Guo, Ben S. Wittner, Joanna A Vuille, Michael S. Lawrence, Chin-Lee Wu, Mehmet Toner, David T. Miyamoto, Shyamala Maheswaran. Hypomethylation of immune-related loci contribute to prostate tumorigenesis [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr IA010.
Abstract B049: Breast cancer-derived angiopoietin-like 7 regulates necrotic core formation and metastasis from the tumor interior
Authors: Ami Yamamoto, Yin Huang, Brad A. Krajina, Margaux McBirney, Andrea E. Doak, Carolyn L. Wang, Michael C. Haffner, Kevin J. Cheung
Journal: Cancer Research (2023)

Abstract Necrosis in the tumor interior is a common feature of aggressive cancers that is associated with poor clinical prognosis and the development of metastasis. However, how the necrotic core promotes tumor cell dissemination and metastasis remains unclear. Foundational models for cancer metastasis research include mouse, zebrafish, and chick embryo, but identifying tumor cells in transit is painstaking. Here we used a rat model of breast cancer metastasis to increase detection of dissemination events. Owing to the large size and higher blood volume of rats, we collected 10 times more circulating tumor cells (CTCs) than from mice. In the rat model, tumor dissemination was temporally correlated with the emergence of necrosis in the tumor interior. These findings were corroborated by longitudinal study of CTC abundance and tissue necrosis markers in blood plasma from patients with metastatic breast cancer. Further, we observed that dilated blood vessels were located next to necrotic regions of the tumor and that their increase was concurrent with the initiation of intratumoral necrosis and increase in CTC abundance. Bulk RNA sequencing of mouse-to-rat xenograft tumor necrotic core compared to the non-necrotic rim revealed distinct tumor-specific and host-specific transcripts in the necrotic interior. We identified angiopoietin-like 7 (Angptl7) as a tumor-specific factor localized to the peri-necrotic zone. Functional studies showed that Angptl7 loss normalizes central necrosis, peri-necrotic dilated vessels, metastasis, and reduces circulating tumor cell counts to nearly zero. Mechanistically, Angptl7 promoted vascular permeability and supported vascular remodeling in the peri-necrotic zone. Taken together, these findings show that breast tumors actively produce factors controlling central necrosis formation and metastatic dissemination from the tumor core. Tumor dissemination events are localized spatially to dilated peri-necrotic vessels in the tumor interior, and tumor dissemination is dependent functionally on the expression of a factor, Angptl7, produced by peri-necrotic tumor cells. Our findings in breast cancer models, in conjunction with recent clinical observations, provide strong evidence for tumor dissemination from the tumor interior. Citation Format: Ami Yamamoto, Yin Huang, Brad A. Krajina, Margaux McBirney, Andrea E. Doak, Carolyn L. Wang, Michael C. Haffner, Kevin J. Cheung. Breast cancer-derived angiopoietin-like 7 regulates necrotic core formation and metastasis from the tumor interior [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr B049.
Abstract PR004: Mechanistic basis for TGF-β-induced fibrogenic EMTs in metastasis
Authors: Jun Ho Lee, Harihar Basnet, Francisco Sánchez-Rivera, Zhenghan Wang, Liangji Li, Joan Massagué
Journal: Cancer Research (2023)

Abstract The cytokine TGF-β is a central regulator of tissue homeostasis and regeneration through multiple coordinated effects on epithelial, immune, and mesenchymal stromal systems. Malfunctions of TGF-β signaling cause fibrosis, immune dysfunction, and cancer. As part of its multifunctional program, TGF-β induces epithelial-mesenchymal transitions (EMTs). Carcinoma cells use TGF-β to undergo EMT and adopt a highly plastic phenotype that facilitates tumor growth and metastasis. Notably, TGF-β-induced EMTs in epithelial progenitor cells are accompanied by the expression of fibrogenic factors that activate fibroblasts to produce and remodel the extracellular matrix. This not only occurs during wound healing but also in lung adenocarcinoma (LUAD) and pancreatic adenocarcinoma (PDAC) cells, suggesting that EMT and fibrogenesis are parts of an orchestrated program. We recently showed that the transcription factor RAS-Responsive Element-Binding Protein 1 (RREB1) activated by RAS-MAPK signaling synergizes with SMADs to coordinately activate the expression of EMT transcription factor Snai1 and fibrogenic genes in carcinoma progenitors (Su et al Nature 2020). Using metastasis transplantation models, we have now found that both arms of the RREB1-dependent TGF-β responses are important for metastasis. Knockout of individual fibrogenic genes in cancer cells inhibited metastasis without altering the induction of EMT by TGF-β. To address why these TGF-β target genes specifically require KRAS-activated RREB1 for transcriptional induction, we employed proteomics approaches coupled with a CRISPR-based genetic screen. With this approach we identified DXH9 and INO80 as RREB1-interacting factors essential for TGF-β activation of fibrogenic EMT programs in PDAC and LUAD cells. DXH9 and INO80 are helicases that interact and SMAD3 and RREB1 in response to TGF-β. Knockout of Dhx9 or Ino80 abolished the induction of Snai1 and fibrogenic genes by TGF-β, inhibited the LUAD metastasis, and decreased intratumoral fibrosis, thus phenocopying the knockout of Rreb1. The helicase domain of DHX9 is required for TGF-β gene responses and metastasis. Our evidence indicates that RREB1, DXH9, and INO80 function to remodel the chromatin at specific loci that constitute a TGF-β-dependent fibrogenic EMT program. This work illuminates a previously unknown cooperation between TGF-β and RAS-MAPK pathways during epithelial tissue regeneration and its cooption in carcinoma metastasis. Citation Format: Jun Ho Lee, Harihar Basnet, Francisco Sánchez-Rivera, Zhenghan Wang, Liangji Li, Joan Massagué. Mechanistic basis for TGF-β-induced fibrogenic EMTs in metastasis [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr PR004.
Abstract IA023: Tailored investigation and treatment of the brain metastasis micronich
Authors: Melanie Hayden Gephart
Journal: Cancer Research (2023)

Abstract Brain metastases are highly aggressive, treatment-resistant malignancies with debilitating neurological sequelae and a grave prognosis. Common intrinsic features of the tumor and extrinsic features of the brain microenvironment, are relevant for cancer brain tropism and response to therapies. Efforts to understand, modulate, and target the metastatic brain tumor microenvironment have tremendous therapeutic potential. Citation Format: Melanie Hayden Gephart. Tailored investigation and treatment of the brain metastasis micronich [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr IA023.
Abstract B009: Tumoral activation of endothelium drives macrophages-mediated metastatic niche formation and promotes lung metastasis
Authors: Hyewon Chung, Sang Wha Kim, Seung Hyeok Seok
Journal: Cancer Research (2023)

Abstract Primary tumor induces macrophages-enriched environment to establish metastatic niche which enhances homing and colonization of circulating tumor cells. However, the molecular mechanism underlying endothelial remodeling that favors macrophages infiltration and subsequent niche formation is not fully understood. Here, we found that tumor-derived factors activated endothelial cells to increase adhesive efficacy of monocytes to the endothelium, leading to macrophage infiltration. In mouse models of pulmonary metastasis, this endothelial activation triggered formation of premetastatic niche via accumulation of macrophages in the lungs. Of note, macrophages primed the metastatic microenvironment through enhancing expression of niche-related genes including S100A8, S100A9, MMP9 and fibronectin within the premetastatic lungs and directly transmitted survival signal to tumor cells in a contact-dependent manner. Furthermore, we demonstrated that depletion of macrophages specifically during premetastatic stages reduced niche formation and also resulted in reduced metastatic burden. These findings suggest that endothelial remodeling at metastatic site is a key step for initiation of premetastatic niche formation supported by macrophages. Targeting this step could present an opportunity for therapeutic intervention of metastatic spread in patients with malignant cancers. Citation Format: Hyewon Chung, Sang Wha Kim, Seung Hyeok Seok. Tumoral activation of endothelium drives macrophages-mediated metastatic niche formation and promotes lung metastasis [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr B009.
Abstract PR003: OXPHOS impairing mitochondrial DNA mutations suppress melanoma growth and metastatic progression
Authors: Spencer Shelton, Sara House, Vijayashree Ramesh, Zhengkang Chen, Claire Llamas, Alpaslan Tasdogan, Ralph DeBerardinis, Sean Morrison, Prashant Mishra
Journal: Cancer Research (2023)

Abstract Cancers acquire somatic mitochondrial DNA (mtDNA) mutations undetected in surrounding tissues. Cancer-specific mtDNA mutations primarily constitute variants of unknown significance whose oncogenic consequences are poorly understood. Analysis of large-scale sequencing datasets suggests that human cancers generally select against severe mtDNA mutations; however, the presence of selective pressure on the mtDNA genome has yet to be experimentally demonstrated. Here we optimized a FACS-based protocol to reconstitute the highly metastatic human melanoma cell line A375 with exogenous mtDNA, thereby generating nuclear-isogenic cytoplasmic hybrid (cybrid) lines. Homoplasmic cybrids were generated exclusively harboring either exogenous wildtype mtDNA, mtDNA with partial loss of OXHPHOS function (SNPs in mt.ND1 (of Complex I) or mt.ATP6 (of Complex V)), or mtDNA with complete loss of OXPHOS function (derived from a human melanoma harboring a truncating frameshift mutation in mt.CO1 (of Complex IV)). Compared to wildtype cybrids, subcutaneous xenografts of ND1 and ATP6 cybrids into NOD–SCID Il2rg−/− (NSG) mice had elevated primary tumor ROS levels and similar primary tumor growth rates. Xenografts of our most dysfunctional OXPHOS cybrid, CO1, formed tumors albeit with lowered growth rates. Uniquely, the ND1 and CO1 xenografts respectively exhibited diminished metastatic burden and no metastatic burden. Our results suggest that OXPHOS impairing mtDNA mutations are tolerable during primary tumor growth but reduce the severity and incidence of metastasis. Lastly, we generated heteroplasmic A375 cybrids, harboring both wild-type and mutant alleles, and developed a ddPCR method to characterize allelic frequency with single-cell precision. Extended in vitro passage of the heteroplasmic cybrids failed to significantly shift the heteroplasmic mtDNA allelic frequency. However, following subcutaneous xenografting of the heteroplasmic cybrids, primary tumors significantly shifted their variant allele frequency to favor the wildtype allele. In summary, these results indicate that a functional mtDNA haplotype is not absolutely required for tumorigenesis but contributes to metastatic efficiency. In addition, we experimentally demonstrated the existence of selective pressure in favor of functional mtDNA during tumorigenesis. Citation Format: Spencer Shelton, Sara House, Vijayashree Ramesh, Zhengkang Chen, Claire Llamas, Alpaslan Tasdogan, Ralph DeBerardinis, Sean Morrison, Prashant Mishra. OXPHOS impairing mitochondrial DNA mutations suppress melanoma growth and metastatic progression [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr PR003.
Abstract 14685: RP105, A Cell Surface TLR4 Signaling Regulator, Enhances Atherosclerotic Plaque Formation
Authors: Jacco C Karper, Saskia C de Jager, Mark Ewing, J W Jukema, Johan Kuiper, Paul H Quax
Journal: Circulation (2011)

Introduction RP105 is a structural homolog of TLR4 and an important regulator of TLR4 signaling. RP105 enhances TLR4 signaling in B-cells while it dampens the TLR4 response on myeloid cells. B-cell...